Exposure to fine particle mass and number concentrations in urban transportation environments of New York City

Travelers’ real-time exposure to fine particles is assessed in terms of particle mass and number concentrations across various transportation-related micro-environments in New York City. Substantial spatial/temporal variations were observed in both the mass and number metrics of fine particles. Comparisons of exposure levels to fine particles across location categories reveals significant differences between particle mass and number concentration measurements; while the highest particle number concentration is on urban street sides, subway trains, with the lowest fine particle number concentration, has the second highest mass. Statistical analysis confirms this disparity.

► PM2.5 and PM number concentration were measured in several transportation environments in NYC.
► Results revealed discrepancy of spatial patterns between the two measures.
► Statistical significance of the discrepancy was confirmed by a mixed-effect linear model.